Microprocessor controlled prosthetic ankle system for footwear and terrain adaptation

ABSTRACT

A prosthetic ankle includes a pair of prosthetic members movably coupled together to allow movement of the pair of prosthetic members with respect to one another. A hydraulic actuator or damper including hydraulic fluid in a hydraulic chamber is coupled to one of the pair of prosthetic members. A hydraulic piston is movably disposed in the hydraulic chamber and coupled to another of the pair of prosthetic members. A hydraulic flow channel is fluidly coupled between opposite sides of the chamber to allow hydraulic fluid to move between the opposite sides of the chamber as the hydraulic piston moves therein. A voice coil valve is coupled to the hydraulic flow channel to vary resistance to flow of hydraulic fluid through the flow channel, and thus movement of the piston in the chamber, and thus influencing a rate of movement of the pair of prosthetic members with respect to one another.

RELATED APPLICATION(S)

Priority is claimed to U.S. Provisional Patent Application Ser. No.61/870,704, filed Aug. 27, 2013, which is hereby incorporated herein byreference.

RELATED APPLICATION(S)

This is related to U.S. patent application Ser. No. 13/829,714, filedMar. 14, 2013, and entitled “Prosthetic with Voice Coil Valve”; which ishereby incorporated herein by reference.

This is related to U.S. patent application Ser. No. 13/793,892, filedMar. 11, 2013, and entitled “Hydraulic Prosthetic Ankle”, which claimspriority to U.S. Provisional Patent Application Ser. No. 61/761,003,filed Feb. 5, 2013; which are hereby incorporated herein by reference.

This is related to U.S. Pat. No. 8,746,080 (application Ser. No.13/015,423, filed on Jan. 27, 2011), and entitled “Compact and RobustLoad and Moment Sensor”, which claims priority to U.S. ProvisionalApplication Ser. No. 61/304,367, filed Feb. 12, 2010; which are herebyincorporated herein by reference.

BACKGROUND

1. Field of the Invention

The present invention relates generally to prosthetics with a hydraulicdamper or actuator. More particularly, the present invention relates toa prosthetic ankle.

2. Related Art

The development of a prosthetic ankle with a more natural function orgait is an ongoing endeavor. Examples of prosthetic ankles include U.S.Pat. No. 6,443,993 (Koniuk); U.S. Pat. No. 2,843,853 (Mauch); and U.S.Pat. No. 7,985,265 (Moser).

Prosthetic ankles can incorporate a hydraulic damping scheme to limit orcontrol movement about the ankle, and/or to allow limited range ofmotion for the foot to provide a natural gait on slops or inclinedsurfaces. The hydraulic damping systems often utilize a solenoid valveto limit or resist the flow of hydraulic fluid. A solenoid valve istypically on or off, and can typically operate by drawing a plunger intoan activated magnetic coil and against a spring, which spring can returnthe plunger when the coil is deactivated. In addition, some hydraulicdamping systems may also, or in the alternative, utilize a steppermotor. Furthermore, some hydraulic damping systems can utilize a magnetorheological fluid. Alternatively, some hydraulic damping systems canutilize mechanical controls.

In addition, side loads are commonplace in prosthetic devices. Sideloads cause, at a minimum, premature failure of hydraulic cylinderseals, and at the worst, binding or bending of the cylinder components,especially the shaft. The typical approach to eliminate side loads on ahydraulic cylinder is to mount it with spherical ball joints (also knownas Heim joints) at both ends. In this way, side loads are nottransmitted to the cylinder because the spherical ball joints move toaccommodate the side loads. In prosthetic devices, using spherical balljoints can be impractical because this greatly increases the eye-to-eyelength of the cylinder, but the cylinder must fit within the anatomicalenvelope of a natural leg. For this reason, most prosthetic devices thatemploy a hydraulic cylinder have the cylinder mounted on trunnions. Buttrunnions will transmit side loads.

Prior art prosthetic ankles often do not meet the advanced demandsneeded by today's amputee.

SUMMARY OF THE INVENTION

It has been recognized that it would be advantageous to develop aprosthetic foot that can provide a limited range of motion of the footabout an ankle joint that provides a more natural gait and/or feel.

In addition, it has been recognized that prior art solenoid valves inhydraulic prosthetics lack an ability to finely adjust rates of fluidflow; and that prior art stepper motor control valves in hydraulicprosthetics lack response time to control fluid in both directions,often resulting in parallel systems with double the weight andcomplexity. It has been recognized that it would be advantageous todevelop a prosthesis, and namely an ankle prosthesis or prostheticankle, and/or a hydraulic damper or actuator for such prosthesis, and/ora control valve for such a prosthesis or hydraulic system, that providesbi-directional positioning, proportional control, rapid response and/orlow power consumption.

In addition, it has been recognized that it would be advantageous toincorporate a voice coil valve, rather than a solenoid valve, into aprosthetic ankle, and to address size issues that such a voice coilvalve may raise. Furthermore, it has been recognized that a voice coilvalve can provide reciprocal or bidirectional movement based on thepolarity of an applied current (as opposed to the unidirectionallydriven movement in that the armature of a solenoid that only moves inone direction regardless of the polarity of the current applied, andthat requires a spring for return movement). It has further beenrecognized that the force produced by the voice coil actuator isproportional (and substantially linear) to the current applied (and thevelocity of the coil is proportional to the voltage applied), unlike asolenoid (with non-linear time and force response, and higher powerconsumption towards one end of the stroke due to the need of constantlyworking against the return spring force). Thus, the actuator has asubstantially linear time and force response. The movement and force ofthe voice coil motor is based on the Lorentz Force principle andequation, unlike a spring returned solenoid.

In addition, it has been recognized that it would be advantageous todevelop a prosthetic ankle to reduce or eliminate failure of hydrauliccylinder seals, and binding or bending of other cylinder components,such as the shaft. It has been recognized that it would be advantageousto develop a prosthetic ankle to accommodate side loads while reducingor maintaining the length of the cylinder.

In addition, it has been recognized that it would be advantageous todevelop a prosthetic ankle that can change the position (ankle positionor relative angle between the foot and the shank link) at whichhydraulic resistance is applied by a control algorithm. It has beenrecognized that it would be advantageous to develop a prosthetic anklewhich can lock the position of the hydraulic cylinder based on thepatient's preference, the heel height of the current footwear, and/orthe slop of the terrain.

In addition, it has been recognized that it would be advantageous todevelop a prosthetic ankle that can utilize a wireless connectionbetween the prosthesis and a user interface to allow the patient to movefreely. In addition, it has been recognized that it would beadvantageous to utilize a user interface or application software alongwith the wireless connection between the interface and the prosthesisthat initiates a session that, if interrupted by an interruption in thewireless connection, would allow the session to resume when the wirelessconnection is reestablished.

In addition, it has been recognized by the inventors of the presentinvention that it would be advantageous to mechanically lock a hydraulicankle. The present inventors have recognized that a hydraulic ankle witha large range of motion (e.g. 30 degrees), while providing manyadvantages (such as comfort while sitting, the ability to use footwearwith high heels, the ability to go up and down steep hills or ramps,etc.), also can pose a safety risk. The mechanical lock that can beengaged by the patient mitigates safety risks. The mechanical lock canbe used to improve safety in the case of a system failure such as a deadbattery, a broken wire, etc. It can also be used to improve safety insituations where the patient would not want any unexpected ankle motionto occur, such as driving a car, climbing a ladder, etc. In addition toimproved safety, the mechanical lock can also provide convenience forthe clinician. The clinician can lockout the ankle during dynamicalignment of the prosthetic leg using the mechanical lock. This allowsthe clinician to focus on the alignment without having to worry aboutthe hydraulic settings at the same time.

Furthermore, it has been recognized that it would be advantageous todevelop a prosthetic ankle with a hydraulic system that can quicklyreturn fluid to a main oil chamber through a low resistance path of acheck valve once a high pressure event is over to insure that the highpressure event does not cause a long-term “dead band” in the cylinderbecause the cylinder has effectively lost fluid from the main oilchamber into the IFP chamber.

The invention provides a prosthetic ankle with a pair of prostheticmembers, comprising a shank link configured to be coupled to a remnantlimb of an amputee and an artificial foot, movably coupled together toallow movement of the pair of prosthetic members with respect to oneanother. A hydraulic actuator or damper includes a hydraulic fluid in ahydraulic chamber coupled to one of the pair of prosthetic members; anda hydraulic piston movably disposed in the hydraulic chamber and coupledto another of the pair of prosthetic members. A hydraulic flow channelis fluidly coupled between opposite sides of the chamber to allowhydraulic fluid to move between the opposite sides of the chamber as thehydraulic piston moves therein. A voice coil valve is coupled to thehydraulic flow channel to vary resistance to flow of hydraulic fluidthrough the flow channel, and thus movement of the piston in thechamber, and thus influencing a rate of movement of the pair ofprosthetic members with respect to one another

In accordance with a more detailed aspect of the present invention, thevoice coil valve can open or close flow of hydraulic fluid through theflow channel, and thus allow or disallow movement of the piston in thechamber, and thus unlock or lock movement of the pair of prostheticmembers with respect to one another.

In accordance with another more detailed aspect of the presentinvention, the artificial foot can be pivotally coupled to the shanklink. A flexure can mount the hydraulic actuator or damper to the shanklink or the artificial foot, and having a high stiffness in a directionparallel to a line-of-action of the hydraulic chamber to effectivelytransmit forces to and from the chamber, and having a low stiffness inat least one direction perpendicular to the line-of-action to resistside loads from being transmitted to the chamber.

In accordance with a more detailed aspect of the present invention, aflexure based foot coupler mount can be attached to the artificial foot,and coupled between the artificial foot and the shank link, and coupledbetween the artificial foot and the hydraulic actuator or damper. Asingle-axis pivot can be in the foot coupler mount about which the shanklink and the artificial foot pivot with respect to one another. Ahydraulic pivot can be in the foot coupler mount about which thehydraulic chamber or piston pivots with respect to the artificial foot.A flexure can be in the foot coupler mount between the pivots, and canbe capable of flexing under an applied force or torque to center thehydraulic chamber or piston to the shank link.

In accordance with another more detailed aspect of the presentinvention, the prosthetic ankle can include a housing carried by theshank link and surrounding at least a portion of the shank link. Acontrol system can be disposed in the housing. A battery can beelectrically coupled to the control system and disposed in the housing.The housing, with the control system and the battery therein, can bedisposed in an anatomical envelop of a natural leg. The housing, theshank link and the hydraulic actuator or damper can be disposed in theanatomical envelop of a natural leg.

In accordance with another more detailed aspect of the presentinvention, the shank link can include a yoke with a pair of armsextending towards and coupled to the artificial foot. The voice coilvalve and the hydraulic actuator can be at least partially disposedbetween the pair of arms of the yoke.

In accordance with another more detailed aspect of the presentinvention, the voice coil valve can be disposed in and carried by thepiston, and movable with the piston inside the hydraulic chamber. Inaddition, the hydraulic channel can extend through the piston.

In accordance with another more detailed aspect of the presentinvention, the prosthetic ankle can include foot coupler mount attachedto the artificial foot. The shank link can comprise a yoke with a pairof arms extending towards and pivotally coupled to the foot couplermount at a single-axis pivot. A force sensor, or a torque sensor, orboth can be carried by the prosthetic ankle to measure force, torque, orboth applied by the user to the prosthetic ankle or artificial foot. Agyroscope, or an accelerometer, or both can be carried by the footcoupler mount or the artificial foot. An angle sensor can be carried byan ankle shaft of the pivot to measure relative angle between the shanklink and the artificial foot. A control system can be coupled to thevoice coil valve and the sensors. The control system can include a valvecontroller carried by the hydraulic chamber and disposed between thepair of arms of the yoke, and a main controller disposed on both sidesof the yoke.

In accordance with another more detailed aspect of the presentinvention, the prosthetic ankle can include a foot coupler mountattached to the artificial foot. The shank link can comprise a yoke witha pair of arms extending towards and pivotally coupled to the footcoupler mount at a single-axis pivot. A force sensor, or a torquesensor, or both can be carried by the prosthetic ankle to measure force,torque, or both applied by the user to the prosthetic ankle orartificial foot. A gyroscope, or an accelerometer, or both can becarried by the foot coupler mount or the artificial foot. An anglesensor can be carried by an ankle shaft of the pivot to measure relativeangle between the shank link and the artificial foot. A control systemcan be coupled to the voice coil valve and the sensors. The controlsystem: opens the voice coil valve when the artificial foot isun-weighted to allow the artificial foot to pivot with respect to theshank link to allow for terrain adaptation; and closes the voice coilvalve when the artificial foot is weighted to lock the artificial footwith respect to the shank link to allow the artificial foot to function.

In accordance with another more detailed aspect of the presentinvention, the prosthetic ankle can include at least three differentfoot covers or shells having different outer sizes and each having acavity therein. The artificial foot and at least a portion of the shanklink and the hydraulic actuator or damper can fit in each cavity of theat least three different foot covers.

In accordance with another more detailed aspect of the presentinvention, the voice coil valve can include a permanent magnet and acoil movable with respect to the permanent magnet. A spool can becoupled to the coil and movable therewith, and disposed in andcircumscribed by both the coil and the magnet.

In accordance with another more detailed aspect of the presentinvention, the prosthetic ankle can comprise a mechanical ball lockcarried by a piston rod of the hydraulic piston, and releasablyengagable with the hydraulic chamber, to lock the hydraulic piston andthe hydraulic chamber with respect to one another. The mechanical balllock can comprise a collar rigidly affixed to the hydraulic chamber andan indentation in the interior of the collar. The piston rod can extendthrough the collar and can have a hollow therein. At least one hole canbe in the piston rod, and at least one ball can be movably disposed inthe at least one hole of the piston rod. An engagement pin can bemovably disposed in the hollow of the piston rod. The engagement pin canhave an enlargement to displace the at least one ball partially into theindentation in the interior of the collar when the indentation isaligned with the at least one hole so that the at least one ball is inboth the at least one hole and the indentation to lock the piston rodand the collar with respect to one another.

In addition, the invention provides a prosthetic ankle with a pair ofprosthetic members, comprising an shank link configured to be coupled toa remnant limb of an amputee and an artificial foot, movably coupledtogether to allow movement of the pair of prosthetic members withrespect to one another. A hydraulic actuator or damper includinghydraulic fluid in a hydraulic chamber is coupled to one of the pair ofprosthetic members, and a hydraulic piston is movably disposed in thehydraulic chamber and coupled to another of the pair of prostheticmembers. A hydraulic flow channel fluidly is coupled between oppositesides of the chamber to allow hydraulic fluid to move between theopposite sides of the chamber as the hydraulic piston moves therein. Acontrol valve is coupled to the hydraulic flow channel to open or closeflow of hydraulic fluid through the flow channel, and thus allow ordisallow movement of the piston in the chamber, and thus unlock or lockmovement of the pair of prosthetic members with respect to one another.A controller is coupled to the control valve and has circuitryconfigured to control the control valve based on patient preference, aheel height of footwear coupled to the artificial foot, and/or the slopeof the terrain.

In accordance with another more detailed aspect of the presentinvention, the controller circuitry is configured to change a position(ankle position or relative angle between the foot and the shank link)at which resistance is applied by the control valve to the hydraulicfluid.

In accordance with another more detailed aspect of the presentinvention, the control valve applies a consistent hydraulic resistance.

In accordance with another more detailed aspect of the presentinvention, the controller circuitry is configured to control the controlvalve using:

${x = {{\frac{\left( {x_{CL} - x_{DFR}} \right)}{\left( {\theta_{T} - \theta_{FF}} \right)}\left( {\theta - \theta_{FF}} \right)} + x_{DFR}}},$

where x=a current valve position, x_(CL)=a valve position at which avalve orifice of the control valve is completely closed, x_(DFR)=a valveposition selected by the amputee that produces an amount of initialdorsiflexion resistance, θ=a current ankle position angle, θ_(T)=anankle position angle at which the hydraulic ankle will switch to into alocked state, and θ_(FF)=an ankle position angle when the foot of thedevice is flat on the ground or when the device initiates a hydraulicdorsiflexion state.

In accordance with another more detailed aspect of the presentinvention, the controller circuitry is configured to control the controlvalve using:

θ_(T)=θ_(HH)+δ_(S)+δ_(P),

where θ_(T)=the ankle position angle at which the hydraulic ankleswitches to the locked state, θ_(HH)=a default ankle position angle atwhich a hydraulic ankle switches to the locked state based on a heelheight of the current footwear, δ_(S)=an offset angle from the defaultlocked ankle position based on the slope of the terrain, and δ_(P)=anoffset angle from the default locked ankle position based on userpreference.

BRIEF DESCRIPTION OF THE DRAWINGS

Additional features and advantages of the invention will be apparentfrom the detailed description which follows, taken in conjunction withthe accompanying drawings, which together illustrate, by way of example,features of the invention; and, wherein:

FIG. 1 is a perspective view of a prosthetic ankle in accordance with anembodiment of the present invention, shown with a prosthetic footattached thereto;

FIG. 2 is a side view of the prosthetic ankle of FIG. 1;

FIG. 3 is a top view of the prosthetic ankle of FIG. 1;

FIG. 4 is a front view of the prosthetic ankle of FIG. 1;

FIG. 5 is a rear view of the prosthetic ankle of FIG. 1;

FIG. 6 is an exploded view of the prosthetic ankle of FIG. 1;

FIG. 7 a is a cross-sectional side view of the prosthetic ankle of FIG.1, taken along line 7 a in FIG. 3 (shown with a control valve removed);and

FIG. 7 b is a detailed cross-sectional side view of the prosthetic ankleof FIG. 1, taken along line 7 a in FIG. 3 (shown with the control valveremoved);

FIG. 8 is a perspective view of a hydraulic actuator or damper, orhydraulic system, of the prosthetic ankle of FIG. 1, in accordance withan embodiment of the present invention;

FIG. 9 a is a cross-sectional side view of the hydraulic actuator ordamper, or the hydraulic system, of FIG. 8, taken along line 9 a of FIG.8 (shown in a closed configuration);

FIG. 9 b is a cross-sectional perspective view of the hydraulic actuatoror damper, or the hydraulic system, of FIG. 8, taken along line 9 a ofFIG. 8 (shown in the closed configuration);

FIG. 9 c is a cross-sectional partially exploded perspective view of thehydraulic actuator or damper, or the hydraulic system, of FIG. 8, takenalong line 9 a of FIG. 8 (shown in the closed configuration);

FIG. 10 is a perspective view of the control valve of the prostheticankle of FIG. 1;

FIG. 11 a is a cross-sectional side view of the control valve of FIG.10, taken along line 11 a in FIG. 10, and shown in the closedconfiguration;

FIG. 11 b is a cross-sectional side view of the control valve of FIG.10, taken along line 11 a in FIG. 10, and shown in an openconfiguration;

FIG. 11 c is a cross-sectional perspective view of the control valve ofFIG. 10, taken along line 11 a in FIG. 10, and shown in the closedconfiguration;

FIG. 11 d is a cross-sectional side perspective of the control valve ofFIG. 10, taken along line 11 a in FIG. 10, and shown in the openconfiguration;

FIG. 11 e is a cross-sectional perspective view of the control valve ofFIG. 10, taken along line 11 a in FIG. 10, and shown in the closedconfiguration;

FIG. 11 f is a cross-sectional side perspective of the control valve ofFIG. 10, taken along line 11 a in FIG. 10, and shown in the openconfiguration;

FIGS. 12 a-c are perspective, side and front views, respectively, of theprosthetic ankle of FIG. 1 shown in an anatomical envelope defined by anatural leg and/or ankle and foot;

FIGS. 13-15 are perspective, side and top views, respectively, of aflexure based foot coupler mount of the prosthetic ankle of FIG. 1;

FIG. 16 is a schematic view of the control system of the prosthetic footof FIG. 1.

FIG. 17 a is a perspective view of another hydraulic actuator or damper,or hydraulic system, of the prosthetic ankle shown in accordance withanother embodiment of the present invention;

FIG. 17 b is a side view of the hydraulic actuator or damper, orhydraulic system, of FIG. 17 a;

FIG. 17 c is a cross-sectional side view of the hydraulic actuator ordamper, or hydraulic system, of FIG. 17 a, taken along like 17 c of FIG.17 a, shown in a locked configuration;

FIG. 17 d is a cross-sectional side view of the hydraulic actuator ordamper, or hydraulic system, of FIG. 17 a, taken along like 17 c of FIG.17 a, shown in an unlocked configuration;

FIG. 18 a is a partial perspective view of another prosthetic ankle inaccordance with an embodiment of the present invention, shown with asnap-on bond ring;

FIG. 18 b is a partial, exploded, perspective view of the prostheticankle of FIG. 18 a, shown with the snap-on bond ring;

FIG. 18 c is a partial perspective view of the prosthetic ankle of FIG.18 a, shown with a cap; and

FIG. 18 d is a partial, exploded, perspective view of the prostheticankle of FIG. 18 a, shown with the cap;

FIG. 19 a is a graph of valve position and hydraulic resistance versustime for the prosthetic ankle in accordance with a embodiment of thepresent invention; and

FIG. 19 b is a contrasting graph of valve position and hydraulicresistance versus time.

In the above mentioned figures, hydraulic fluid has been removed forvisibility of the components. Although the hydraulic fluid is not shown,those skilled in the art will clearly understand the volumes itoccupies, and the channels it flows through.

Reference will now be made to the exemplary embodiments illustrated, andspecific language will be used herein to describe the same. It willnevertheless be understood that no limitation of the scope of theinvention is thereby intended.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENT(S)

The invention provides a prosthetic ankle or joint device for use by anamputee. The prosthetic ankle can have or can be an active dampeningankle joint with limited dorsiflexion-plantarflexion (up and down)pivoting to accommodate footwear of varying heel heights or differentenvironments, such as inclined terrain, by allowing a foot or foot keelor artificial foot to pivot about a horizontal medial-lateral (lateralside-to-side) pivot axis to accommodate the heel height or incline. Forexample, the foot keel or artificial foot can pivot in plantarflexion(toe pivoting downwardly) for an increase in heel height or when adownward slope is encountered; or the foot keel or artificial foot canpivot in dorsiflexion (toe pivoting upwardly) for a decrease in heelheight or when an upward slop is encountered.

The prosthetic ankle device or prosthetic ankle can have an entiresystem, including control systems, batteries, etc., contained in ahousing and in an anatomical envelope defined by a natural leg and/orankle and foot. In addition, the prosthetic foot can incorporate a valvedirectly driven by a voice coil or a voice coil valve to control ahydraulic actuator or damper. The voice coil driven valve allows for avalve that is compact, relatively low power, has a fast response time,and has a large dynamic range (that works at both high pressures and lowpressures). In addition, the hydraulic system can be mechanicallycoupled with a flexure-based mechanical system to adjust for side loads.A flexure built into the mounting structure of the hydraulic cylindercan effectively transmit forces to and from the cylinder, whilepreventing or resisting or minimizing side loads. In addition, the voicecoil driven valve can be carried by a piston in a cylinder or chamber ofthe hydraulic system. In addition, the voice coil driven valve orcontrol valve can be controlled by a controller with an algorithm thatchanges a position (ankle position or relative angle between the footand the shank link) at which hydraulic resistance is applied; can varyresistance to flow of hydraulic fluid through the flow channel, and thusmovement of the piston in the chamber, and thus influencing a rate ofmovement of the pair of prosthetic members with respect to one another;and can be a function of a patient's preference, a heel height ofcurrent footwear, and/or a slope of the terrain (or combinationsthereof). In addition, a mechanically ball lock can lock the hydraulicpiston and the hydraulic chamber with respect to one another to lock theprosthetic ankle. In addition, a wireless connection between a userinterface and the controller of the prosthetic ankle can allow thepatient to move freely while a prosthetist or a clinician makesadjustments; while the user interface can utilize a session that allowsthe wireless connection to be momentarily interrupted with minimalimpact. In addition, the prosthesis or prosthetic ankle or batterythereof can be charged with electromagnetic resonant wireless chargingwith magnetically coupled and resonantly tuned transmitter and receiver.In addition, an orifice and a check valve can be place in parallelbetween the hydraulic chamber and a variable volume to allow a springbiased piston in the variable volume to quickly return fluid to thehydraulic chamber through the check valve following a high pressureevent to reduce or eliminate long-term “dead band” in the chamber toachieve high pressure in both compression and extension. Furthermore,the prosthetic ankle can fit within multiple different, and standard,foot covers or shells.

The prosthetic ankle can have a pair of prosthetic members that aremovably and/or pivotally coupled to one another, and can move and/orpivot with respect to one another, and can be locked with respect to oneanother and/or have relative movement resisted. For example, the pair ofprosthetic members can comprise a shank link coupled to a remnant limbof an amputee, and an artificial foot. The artificial foot can be anenergy storing and releasing type foot, such as with leaf springs formedof carbon fibers in a resin matrix. The prosthetic members, or shanklink and artificial foot, can pivot with respect to one another toadjust for slope in the terrain and/or accommodate varying heel heights.In addition, the prosthetic member, or shank link and artificial foot,can be selectively locked with respect to one another to preserve therelative position or orientation of the members, or shank link andartificial foot, and to allow the artificial foot to function (such asto store and return energy during the gait cycle). Thus, during the gaitcycle, the shank link and the artificial foot can be selectively lockedor unlocked. For example, on heel strike (and when substantiallyun-weighted), the artificial foot can be relatively free to pivot(planter-flexion) with respect to the shank link in order to adjust tothe terrain. The ankle or artificial foot can include sensors (e.g.force or load sensor, torque sensor, angle sensor, accelerometer and/orgyroscope) carried by and disposed on the prosthetic ankle and/orartificial foot itself. The movement of the artificial foot with respectto the shank link can provide a comfortable rate of movement as the footprogresses from heel strike to becoming flat on the ground. As the userplaces weight on the artificial foot and the ankle, a predeterminedforce or weight threshold is passed triggering one or more weightedstates or sub-states thereof, such as initial ground search state,mid-stance state, foot flat state, etc. During the weighted states, theartificial foot can be locked or progressively locked or resisted withrespect to the shank link. For example, at mid-stance or foot flatstate, the ankle can be locked or progressively locked.

As stated above, the artificial foot can be a leaf spring or energystoring type artificial foot comprising one or more leaf springs orenergy storing members that are flexible to bend or flex under loading,and resilient to store and return the energy of the bent or flexedsprings or members. For example, such leaf springs can be formed ofcarbon fiber in a resin matrix. The artificial foot can include aforefoot keel coupled to the shank link, and a footplate coupled to theforefoot keel. The forefoot keel can extend from the shank link at anankle location of a natural foot, through an arch and/or ball to a toeat a toe location of a natural foot. The footplate can be coupled at thetoe of the forefoot keel and can extend to a heel at a heel location ofa natural foot. The forefoot keel and the footplate can be split whollyor partially.

The pair of prosthetic members, or shank link and artificial foot, canmove in dorsiflexion (toe up or towards shin) and plantarflexion (toedown or away from shin). The prosthetic members can move and/or pivotabout a single pivot joint or axle.

A hydraulic actuator or damper can also be coupled to and between thepair of prosthetic members, or shank link and artificial foot, tocontrol or limit the movement and/or pivoting between the members. Theterms “hydraulic actuator”, “hydraulic damper” and “hydraulic actuatoror damper” are used interchangeably herein to refer to a hydraulicsystem that imposes some type of limitation or control on the movementof a hydraulic fluid, and thus some type of limitation or control on therelative movement between the prosthetic members. The hydraulic systemcan be a hydraulic damper that simply limits or resists movement of thehydraulic fluid, and thus simply limits or resists movement between thepair of prosthetic members. The hydraulic system can be a hydraulicactuator that includes a hydraulic motor that drives or createshydraulic pressure to drive movement between the pair of prostheticmembers. Such a hydraulic actuator can also be operated as a damper.

The hydraulic system can include a hydraulic separator, such as a pistonor vane, movable in a hydraulic chamber, such as a linear cylinder orrotary chamber, to displace hydraulic fluid from one side of the workingchamber to the other. The piston can be coupled to one of the prostheticmembers (e.g. the artificial foot), while the chamber is coupled to theother of the prosthetic members (e.g. the shank link) in the embodimentof a linear piston damper. Such couplings can be secondary pivotalcouplings, separate from a primary pivot between the pair of members.The piston can divide the chamber into opposite sides and the hydraulicsystem can be configured to displace the fluid from one side of thepiston to the other, or from one side of the chamber to the other. Thus,the hydraulic system can have a hydraulic flow channel fluidly coupledbetween the opposite sides of the chamber to allow the hydraulic fluidto move between the opposite sides of the chamber as the piston movestherein. In one aspect, the hydraulic system can include an overflowreservoir to accommodate the different volumes of the opposite sides ofthe chamber due to the volume of piston rod coupled to the piston. Inanother aspect, the hydraulic system can include a piston rod on bothsides of the piston, which exits the working chamber on both sides,commonly termed a “thru-rod” damper, so that the sum of the volume onboth sides of the chamber during the stroke remains constant.

A control valve can be coupled to the hydraulic flow channel to varyresistance to the hydraulic fluid flow or vary the flow rate. Prior artsolenoid valves have been used to vary flow. Solenoid valves typicallyhave a stationary iron core with a coil, and a movable iron armaturethat is moved when current is applied to the coil. Solenoid valves alsotypically rely on a spring for return movement when the current isremoved from the coil. Thus, solenoid valves often have an on-offoperation. Solenoid valves generate force proportional to the square ofthe current (and are thus non-linear). Solenoids are relativelyinexpensive. It has been recognized by the inventors, however, thatsolenoid valves are or can be limited by unidirectionally drivenmovement in that the armature only moves in one direction regardless ofthe polarity of the current applied, and that a spring is required forreturn movement. In addition, it has been recognized by the inventorsthat solenoid valves are or can be limited by requiring additionalcurrent to overcome the spring force of the spring, thus requiringgreater power consumption. In addition, it has been recognized by theinventors that solenoid valves are or can be limited by slower responsetimes and/or non-linear response time (and force).

The inventors have recognized that the control valve can include anelectric actuator, coupled to a hydraulic valve, to reciprocally andselectively position the valve, or spool thereof, in a bidirectionalmovement based on the polarity of the current applied to the actuator.Thus, the valve can be bi-directionally driven in back and forthdirections, and bi-directionally positioned. The electric actuatorincludes a permanent magnet and a coil movable with respect to oneanother. The permanent magnet can have a magnetic field in which thecoil moves when a current is applied to the coil. As well, the sameresponse can be generated when the magnet moves, and the coil remainsstationary, when electricity is used. The amount of current can beselected and varied to selectively position the coil with respect to themagnet. The polarity of the current can be selected and changed toselect and change the direction of travel of the coil with respect tothe magnet. The force produced by the actuator is proportional (andsubstantially linear) to the current applied (and the velocity of thecoil is proportional to the voltage applied), unlike a solenoid (withnon-linear time and force response). Thus, the actuator has asubstantially linear time and force response. The movement and force ofthe voice coil motor is based on the Lorentz Force principle andequation, unlike a solenoid. In addition, the direction of movement ofthe coil can be selected, driven and varied by selecting and varying thepolarity of the current, unlike a solenoid (which has the same directionof travel irrespective of polarity; i.e. changing the polarity of asolenoid does not alter the direction). Thus, the direction of travel ofthe coil is based on the polarity of the current. The actuator, and thusthe valve, has a rapid response rate (i.e. greater than 100 cycles persecond), and a low power consumption (i.e. less than 1.8 Watts, or 150mAmps @ 12V), unlike a solenoid. Such an actuator or valve can bereferred to as a voice coil or voice coil valve. The actuator is coupledto the hydraulic valve, which is operatively coupled in the hydraulicflow path. The valve includes an orifice and a spool movable withrespect to one another. The actuator is coupled to the valve to move theorifice and the spool with respect to one another to selectively resistflow of the hydraulic fluid through the orifice. In one aspect, theactuator can move the spool with respect to the orifice. Thus, thehydraulic valve selectively varies the resistance of the hydraulic valveto the flow of hydraulic fluid through the flow channel.

The control valve and electrical actuator thereof can be operativelycoupled, or electrically coupled or wirelessly coupled, to controlelectronics, such as a circuit board with a microprocessor, forming acomputer to control the control valve, and thus the hydraulic system orhydraulic actuator or damper. The computer or control electronics canutilize a control algorithm. The computer or control electronics canvary resistance to flow of hydraulic fluid through the flow channel, andthus movement of the piston in the chamber, and thus influencing a rateof movement of the pair of prosthetic members with respect to oneanother. In addition, the computer or control electronics can open oropen or close the valve (or flow of hydraulic fluid through the flowchannel thereof), and thus allow or disallow movement of the piston inthe chamber, and thus unlock or lock movement of the pair of prostheticmembers with respect to one another. The computer or control electronicscan control the hydraulic valve to vary the flow rate of the hydraulicfluid, and thus the resistance to bending, of the ankle. The computercan vary the compression and extension of the hydraulic system orhydraulic actuator or damper during the gait cycle of a prostheticankle; and thus control the dorsiflexion and plantarflexion of theprosthetic ankle during gait. The computer and the control valve canvary the resistance and the flow rate of the compression and/orextension of the hydraulic system during both dorsiflexion andplantarflexion of the prosthetic ankle or members thereof. The computeror control electronics can change the position (ankle position orrelative angle between the foot and the shank link) at which hydraulicsystem applies resistance. The computer or control electronics canchange the position based on the patient's preference, a heel height ofthe current footwear, and the slope of the terrain. The controlalgorithm can smoothly transition between ankle motion due to both 1)pivoting of the foot about the pivot and deflection of the artificialfoot, and 2) motion only from foot deflection.

As stated above, the prosthetic ankle can include sensors, such as forceor load sensor, torque sensor, angle sensor, accelerometer and/orgyroscope. These sensors can be carried by and disposed on theprosthetic ankle and/or artificial foot itself. For example, a force orload sensor, a torque sensor, or both, can be disposed on or carried bythe shank link or a connector thereof to measure force, torque, or bothapplied by the user to the prosthetic ankle or artificial foot. Asanother example, an angle sensor can be carried by an ankle shaft of thepivot between the shank link and the artificial foot to measure relativeangle between the shank link and the artificial foot. As anotherexample, an accelerometer, a gyroscope, or both can be carried by a footcoupler mount or the artificial foot to sense or measure impact,orientation, etc. Disposing the sensors on the prosthetic ankle and/orartificial foot allows the prosthetic ankle to be a unitary devicewithout components disposed on other structure, such as pylons.Similarly, locating an angle sensor between the shank link and theartificial foot allows relative orientation to be determined withouthaving to determine a relative orientation of other structure, such as apylon, and without having to locate sensors on a pylon.

As illustrated in FIGS. 1-16, a prosthetic ankle or joint, indicatedgenerally at 10, is shown in an example implementation in accordancewith an embodiment of the invention. The prosthetic ankle 10 includes apair of prosthetic members, namely an upper member or shank link 14, anda lower member or artificial foot 18, that are pivotally coupledtogether at a primary pivot and/or single-axis pivot and/or ankle shaft22. The primary pivot 22 can include an axle and bearings. The shanklink 14 can be disposed at a location of a natural ankle, while theartificial foot 18 can be disposed at a location of a natural foot. Theshank link 14 can have a connector 26 at distal end or top thereof, suchas pyramid connectors as known in the art, for attachment to a socket.The force and torque sensor can be an integral part of the connector 26.Various aspects of robust and compact force and torque sensor are foundin U.S. patent application Ser. No. 13/015,423, filed Jan. 27, 2011,which is hereby incorporated herein by reference. It is desirable inprosthetic control systems to measure both the vertical force applied tothe product and the torque applied in the sagittal plane. Because thetorque generates strains that are much greater than those generated bythe force, it is difficult to design a single sensor that measures bothof these signals. The socket can be attached to a remnant limb of theamputee. Such sockets and connectors are known in the art. In use, thelower member or artificial foot can move with respect to the uppermember or shank link in dorsiflexion (toe up or towards shin) andplantarflexion (toe down or away from shin). The upper prosthetic membercan comprise the shank link and the connector.

The shank link 14 can comprise a yoke with a pair of arms extendingtowards and coupled to the artificial foot 18. The distal ends of thepair of arms can be coupled to the artificial foot. The connector 26 canbe affixed to a top of the yoke. A space or gap can be defined betweenthe pair of arms.

The lower member of the pair of prosthetic members can comprise theartificial foot 18 and a coupler or mount. A flexure can be built intothe mounting structure of a hydraulic cylinder. The flexure can have ahigh stiffness (or a relatively higher or greater stiffness with respectto a lower stiffness) in a direction parallel to the line of action ofthe hydraulic cylinder or chamber to effectively transmit forces to andfrom the cylinder or chamber, but can also have a low stiffness (or arelatively lower or lesser stiffness with respect to the higher orgreater stiffness) in at least one direction perpendicular to theline-of-action to prevent or resist side loads from being transmitted tothe cylinder or chamber. The coupler or mount can be a flexure basedfoot coupler mount 30 attached or mounted directly to the artificialfoot 18, and coupled between the artificial foot and the shank link 14(and the hydraulic actuator or damper). The single-axis pivot and/or theankle shaft 22 can be formed in or disposed in the foot coupler mount30, and the shank link and the artificial foot can pivot with respect toone another about the ankle shaft in the foot coupler mount. Inaddition, a hydraulic pivot 32 can be formed in or disposed in the footcoupler mount 30 (and the hydraulic chamber or piston pivots withrespect to the artificial foot about the hydraulic pivot). A flexure 34can be formed in or disposed in the foot coupler mount 30 between thepivots 22 and 32, and can be capable of flexing in a directionperpendicular to the line-of-action of the hydraulic cylinder as aresult of an applied force or torque. The flexure 34 can be formed by areduced cross-sectional area between and with respect to thecross-sectional area of the foot coupler mount 30. The flexure 34 canact as a flexure bearing, and can isolate the hydraulic cylinder fromside loading in the system when a force or torque is applied. Thus, theflexure based foot coupler mount can be capable of preventing excessiveseal wear and/or binding in the hydraulic cylinder. Side loads arecommon in prosthetic devices, and can, at a minimum, cause prematurefailure of hydraulic cylinder seals and, at the worst, can cause bindingor bending of the cylinder components, especially the shaft. In oneaspect, ball joints can be utilized at both ends of the cylinder toresist transmittal of side loads by movement of the ball joints, butsuch ball joints can greatly increases the eye-to-eye length of thecylinder, which may not fit within the anatomical envelope of a naturalleg. In another aspect, the cylinder can be mounted on trunnions, butthe trunnions can transmit side loads. The flexure system can be usedwith trunnions to minimize side loads, while at the same time allowingthe cylinder to fit within the anatomical envelope of the natural leg(as shown in FIGS. 12 a-c). In another aspect, the flexure can be builtinto the shaft.

The prosthetic ankle 10 also has a hydraulic system 40 that can includea hydraulic actuator or damper 50 and a control valve 60. The hydraulicsystem 40 is coupled between the upper and lower members, or shank linkand prosthetic foot 14 and 18. The hydraulic actuator or damper 50includes a hydraulic chamber, namely a cylinder 54, pivotally coupled tothe upper member or shank link 14, and a piston 58 with a piston rod 62pivotally coupled to the lower member or artificial foot 14. The pivotalconnections between the hydraulic actuator or damper and the upper andlower members form secondary pivots, separated from the primary pivot orankle shaft. In another aspect, the coupling of the hydraulic actuatoror damper can be reversed, with the cylinder coupled to the lower memberor artificial foot, and the piston rod coupled to the upper member orshank link. The piston 58 can be cylindrical and can slidably movewithin the cylinder 54. In addition, the piston 58 divides the cylinder54 or chamber into opposite sides. The cylinder 54 can be formed by acylinder disposed between opposite caps 70 and 72, one of which is anupper cap 70 that is pivotally coupled to the upper member or shank link14 (with an axle and bearings), and the other of which is a lower cap 72that has an aperture to slidably receive the piston rod 62. The pistonrod 62 is pivotally coupled to the lower member or artificial foot 18 orfoot coupler mount 30 (with an axle and bearings).

In addition, the linear piston damper system (or piston 58 and cylinder54) can utilize tightly toleranced components which eliminate the needfor elastomeric seals to separate the sides of the hydraulic chamber. Byusing a “metal-on-metal” fit between the piston and cylinder, the sealdrag (or stiction) which would be transferred to the amputee as ajarring or disjointed feeling, can be entirely removed from the system,or greatly reduced. This also provides for greater reliability andlongevity of the system because there is no elastomeric seal to bedamaged or wear out. The precision that can be required to form ahydraulic working chamber capable of locking without weeping can requirea gap between the acting surfaces of the piston and cylinder on theorder of 0.005 mm (0.0002 in). Furthermore, the surface finish that canbe required to facilitate smooth actuation on both surfaces of thepiston and cylinder can be between 0.20 to 0.41 μm (8 to 16 μin) Rafinish.

Hydraulic fluid (not shown for clarity of the components) can fill thecylinder 54 or chamber, and can be displaced from one side of thecylinder 54 or chamber (or piston 58) to the other as the piston 58moves therein. A hydraulic flow channel 66 is fluidly coupled betweenthe opposite sides of the cylinder 54 or chamber (or piston 58) to allowthe hydraulic fluid to move or displace between the opposite sides ofthe cylinder 54 or chamber (or piston 58) as the piston 58 movestherein. The control valve 60 can be carried by the piston 58, andmovably disposed within the cylinder 54. Thus, the hydraulic flowchannel 66 can extend through the piston 58.

As indicated above, the prosthetic ankle 10 and the hydraulic system 40include a control valve 60 coupled to the hydraulic flow channel 66 toopen and close, and/or vary resistance to, flow of hydraulic fluidthrough the flow channel 66, and thus movement of the piston 58 in thechamber 54, and thus unlock or lock, and/or influence a rate of movementof, the pair of prosthetic members 14 and 18 with respect to oneanother. As discussed above, the control valve 60 includes a hydraulicvalve 80 that directly contacts and acts upon the hydraulic fluid, andan actuator 90 that drives and controls the hydraulic valve 80. Thehydraulic valve 80 and the actuator 90 can be fixed together as asingle, operable unit, i.e. the control valve 60, that can be coupled toand carried by the hydraulic system 40, and the hydraulic actuator ordamper 50, such as by the piston 58. Thus, the control valve 60 can beremoved and replaced as a single unit to facilitate repair or customapplications.

The hydraulic valve 80 of the control valve 60 is operatively coupled inthe hydraulic flow path or channel 66, and includes at least one orifice110 and a spool 114 movable with respect to one another to selectivelyresist flow of the hydraulic fluid through the orifice. The spool 114can be selectively positioned with respect to the orifice(s) 110 toselectively close and open the orifice, and/or increase and decrease across-sectional area through which the hydraulic fluid can flow. Thespool 114 can have a center hole 116 therethrough and cross holes 116 aformed laterally through the spool, and can be pressure balanced throughthe center hole 116 and the cross holes 116 a. The spool 114 can have adistal end 118 (or at least one distal opening) that is selectivelypositionable with respect to the orifice 110. The orifice(s) 110 can beformed in a sleeve 122 circumscribing the spool 114. The spool 114 canslide within the sleeve 122. Thus, the spool 114 can be selectivelypositioned by the actuator to selectively position the spool 114 or end118 thereof with respect to the orifice 110, and close or open theorifice, and/or selectively increase and decrease a cross-sectional areathrough which the hydraulic fluid can flow. An outer diameter of thespool 114 can match an inner diameter of the sleeve 122 with a tighttolerance so that the spool and sleeve seal with respect to one another.In another aspect, the sleeve can be coupled to the actuator and moverelative to the spool and/or the orifice could be formed in the spool.In another aspect, the spool can have a distal opening formed laterallythrough the spool that can be selectively positioned with respect to theorifice 110.

As stated above, the electric actuator 90 is coupled to the hydraulicvalve 80 to move the spool 114 with respect to the orifice(s) 110. Theactuator 90 includes a permanent magnet 140 and a coil 144 movable withrespect to one another. The magnet 140 is part of a magnetic circuitthat includes a housing 140 a and a pole piece 140 b both of which aremade from a magnetically conductive material such as low carbon steel.Both the housing 140 a and the pole piece 140 b can be annular, with thehousing circumscribing the pole piece and forming an annular gaptherebetween. The magnet 140 has or creates a magnetic field thatinduces magnetic flux across an air gap between an inside diameter ofthe magnet 140 or housing 140 a and an outside diameter of the polepiece 140 b. The coil 144 can have an annular wall or cup sized to fitin the air gap between the magnet 140 or housing 140 a and the polepiece 140 b. The coil 144 can include wires wrapped or coiled around thewall or cup. Thus, the coil 144 can be movably positioned in themagnetic field of the magnet 140. A current can be applied to the coil144 to move the coil with respect to the magnet 140. As described above,the current applied to the coil 144 in the magnetic field of the magnet140 produces a force that is directly proportional to the electriccurrent applied. In addition, the coil 144, and thus the control valve60, has a substantially linear time and force response. Furthermore, thecoil 144, and thus the spool 114, is bi-directionally driven by thecurrent, or polarity thereof. The electric current applied to the coil144 causes the coil, and thus the spool 114, to move in either a firstdirection or a second direction based on a polarity of the electriccurrent. Thus, the coil 144 and spool 114 are reciprocally positioned byselectively changing the polarity of the electric current applied to theelectric actuator 90 or coil 144 thereof. Thus, the spool 114 can beselectively positioned and bi-directionally driven in back and forthdirections, so that the hydraulic valve 80 selectively varies theresistance, or effective flow area or size of the orifice(s) 110, of thehydraulic valve 80, via the position of the spool 114 with respect tothe sleeve 122, to the flow of hydraulic fluid through the flow channelor orifice(s) 110. The control valve 60 or actuator 90 can have a rapidresponse rate, greater than 100 cycles per second, and a low powerconsumption, less than 1.8 Watts (i.e. or 150 mA @ 12V). Furthermore,the control valve 60, and the coil 144 thereof, can be selectively andproportionally positioned, proportional to an amount of the electriccurrent applied to coil or the control valve. Thus, a selective andvariable amount of electric current with variable polarity applied tothe coil or control valve selectively and proportionally varies theresistance of the control valve, or the hydraulic valve 80 thereof, tothe flow of hydraulic fluid through the flow channel. While the coil hasbeen described above as movable with respect to a permanent magnet, itis contemplated that such a configuration can be reversed, with themagnet coupled to the spool or sliding tube, and movable with respect tothe coil.

The control valve 60 can be characterized as a voice coil actuated valveor voice coil valve, and the actuator 90 can be characterized as a voicecoil. Therefore, the prosthetic ankle 10 and hydraulic system 40 thereofcan utilize a voice coil actuated valve. As noted above, the controlvalve 60 or voice coil valve described above provides bi-directionalpositioning, proportional control, rapid response and/or low powerconsumption. The use of the control valve 60 or voice coil valvedescribed above allows the coil and spool to be driven in eitherdirection without requiring a spring for return motion, which in turnreduces the power consumption of the control valve, which can result inlonger operational periods between charging and/or smaller powersupplies (e.g. batteries), resulting in greater freedom and less weightfor the amputee. In addition, the use of the control valve 60 or voicecoil valve described above allows the hydraulic system 40 and prostheticankle 10 to have a faster response time to provide a more natural gaitto the amputee and/or to provide a more natural transition. The voicecoil valve provides a fast response time (<20 ms), a large pressurerange (up to about 3000 psi), a fully proportional control (can go toany position as opposed to only open or closed), and a low power (about200 mW to hold a static position). Thus, the voice coil valve allows thehydraulic ankle to have smooth motion that can adapt on-the-fly tochanges in terrain and footwear.

The control valve 60 or voice coil valve can be oriented with a path oftravel of the coil 144 and spool 114 parallel with a path of travel ofthe piston 58. The voice coil valve can be disposed in and carried bythe piston, and movable with the piston inside the hydraulic chamber.The hydraulic channel can extend through the piston. In addition, thevoice coil valve and the hydraulic actuator can be at least partiallydisposed in the space or gap between the pair of arms of the yoke. Theposition and orientation of the control valve 60 or voice coil valve cancreate a more compact and smaller profile for the prosthetic ankle, andthus greater freedom, comfort and natural movement for the amputee,because the control valve 60 or voice coil valve can be larger thanprior art solenoid valves.

In addition, the spool 114 can be substantially concentric with and/orsubstantially disposed within the coil 144 (and the magnet 140) toreduce the length of the actuator 90, control valve 60, and hydraulicsystem; thus, reducing the size of the prosthetic ankle to fit with theanatomical envelope defined by a natural leg and/or ankle and foot.

As described above, one or more orifices 110 in the sleeve 122 can beselectively exposed by the end 118 of the spool 114. The orifice(s) 110can have a longitudinally varying width with a discrete change in widthfrom a proximal end to a distal end along a longitudinal length of theorifice. For example, the orifice can have a larger or wider proximalend, and a smaller or narrower distal end. In one aspect, the width ofthe opening can taper from larger to smaller in a continuous transition.In another aspect, the orifice can have two or more discrete widthsformed by orifices sharing a common boundary that is open between theorifices. The orifice(s) can have a larger proximal rectilinear (squareor rectangular) shape and a smaller distal rectilinear shape, whichshare a common boundary and that are open to one another. In anotheraspect, a larger number of orifices(s) and opening(s) can be aligned ormisaligned. In another aspect, the shape, size, number and/or locationof the orifice(s) and/or opening(s) can be configured to provide the twolinear regions.

The Figures show the operation of the hydraulic system 40, the hydraulicactuator or damper 50, the control valve 60 or voice coil valve, thehydraulic valve 80 and electric actuator 90. FIGS. 11 a, c and e, showthe hydraulic system in a locked configuration and the control valve“closed”, which can correspond to locking the artificial foot withrespect to the shank link. Thus, the artificial foot can lock withrespect to the shank link, and the artificial foot can flex or compressunder load. FIGS. 11 b, d and f show the hydraulic system in a flexibleconfiguration with the control valve “open” or less restricted to have agreater flow rate and a lesser resistance. Thus, the artificial foot canmove more rapidly or with lesser resistance. It is noted, however, thatthe artificial foot can move more slowly and with greater resistance(i.e. with the control valve more “closed” or more restricted) dependingon the gait cycle.

Referring to FIGS. 11 a, c and e, the control valve 60 is closed; thepiston 58 is locked in the cylinder 54; and the artificial foot islocked with respect to the shank link.

Referring to FIGS. 9 a-c, 11 b, d and f, the control valve 60 is open;the piston 58 can move in the cylinder 54; and the artificial foot canmove with respect to the shank link. The hydraulic fluid is displaced bythe piston out of one chamber or portion of the cylinder, through thechannel 66 and the hydraulic valve 80 (and orifice 110), and into theother chamber or portion of the cylinder. The hydraulic fluid isdisplaced into the control valve 60 or voice coil valve through and intothe sleeve 122, and through and into the spool 114, and to theorifice(s) 110 in the sleeve.

The hydraulic system 40 or the hydraulic actuator or damper 50, or thepiston 58, the rod 62 and the cylinder 54 with the control valve 60 orvoice coil valve, the hydraulic valve 80 and electric actuator 90therein, can be provided as a discrete unit that can be removed andinstalled on the prosthetic ankle. For example, the rod 62 can becoupled to the foot coupler mount 30 and the cylinder 54 or upper cap 70thereof can be coupled to the shank link 14. In addition, the controlvalve 60 or voice coil valve, the hydraulic valve 80 and electricactuator 90 therein can be provided as a discrete unit that can beinstalled in the cylinder and coupled to the piston 58. The controlvalve 60 or voice coil valve can have a housing 300 (FIGS. 9 c and 10)with an open end 304 that can be coupled to the piston 58. (The actuator90 and the hydraulic valve 80 can be disposed in the housing 300.) Thepiston 58 can have a receptacle or socket 308 (FIG. 9 c) to receive aplug 312 or protrusion in the housing 300 with the open end 304 of thecontrol valve 60. Thus, the piston can carry the control valve. One ormore opening(s) can be formed in an opposite side of the piston,opposite from the receptacle or socket 308, and partially defining theflow channel 66. One or more lateral opening(s) 316 can be formed in thehousing 300 and spaced-apart from the open end 304. The lateralopening(s) 316 can extend through the housing 300 and to the orifice 110in the inner tube 122. Thus, the orifice 110 can be disposed between thelateral opening(s) 316 and the open end 304. The lateral openings 316and the open end 304 can partially define the flow channel 66 throughthe piston.

The housing 300 can also have an opposite plug 320 or protrusionopposite the piston. The opposite plug 320 can receive a top shaft 324that can extend through an opening in the top cap 70. The top shaft 324can have the same diameter and cross-sectional area as the piston rod 62so match the change in volume on each side of the chamber as the pistonmoves. The top shaft can form an opposite rod that can be formed on thepiston on the opposite side of the piston rod so that the total volumeinside the hydraulic cylinder doesn't change as the piston moves. Thethrough rod piston cylinder type hydraulic actuator or damper willrequire a smaller variable volume 501 or reservoir, with a spring and anindependent floating piston (IFP) 503, to operate since the variablevolume only compensates for temperature changes and not fluid displacedby the shaft as equal amounts of shaft or rod enter and leave thecylinder at the same time. This also reduces the cycle life requirementof the variable volume since it moves only when the temperature changes,not every time the piston position changes. The variable volume 501 orreservoir can be formed in the piston rod 62, and can include a springand an independent floating piston (IFP) 503 biased by the spring.

A through rod piston cylinder type hydraulic actuator or damper is usedto create a system that can generate high pressure in both the extensionand compression directions without a spring bias towards extension. Astandard cylinder (rod on only one side of the piston) requires avariable volume to accommodate for the fluid that is displaced by therod as the cylinder is compressed. If high pressure must be generated inthe extension direction of a standard cylinder, then a stiff spring mustbe used in the variable volume. This stiff spring will tend to forcefluid out of the variable volume which will force the shaft out of thecylinder which will extend the cylinder. In the case of thishydraulically controlled ankle, a cylinder spring biased towardsextension would result in an ankle that would tend to plantarflexanytime the foot is un-weighted creating a tripping hazard for theamputee.

The through rod cylinder does not need a stiff spring behind thevariable volume in order to generate high pressure in both directions ifa fixed, small diameter flow orifice 500 is used between the cylinder'smain oil chamber or cylinder 54 and the variable volume 501. In highflow situations as would be expected when the piston moves, the pressuredrop across the orifice 500 is large, thus the cylinder can generatepressure without moving the spring in the variable volume 501. In lowflow situations as would be expected during a temperature change, thepressure drop across the orifice 500 is small, and fluid can move backand forth as necessary between the main oil chamber and the variablevolume 501. There are, however, situations where the pressure limit ofthe cylinder can be exceeded and oil is forced into the variable volume501 through the orifice. Check valve 502 is placed in parallel to theorifice 500 in order to allow any oil forced into the variable volume501 immediately back into the main oil chamber. Otherwise, the hydrauliccylinder would develop a dead band.

Thus, an orifice and a check valve are placed in between the chamberwhere the independent floating piston (IFP) 503 is located and the mainoil chamber of a hydraulic cylinder. The orifice permits only low flowbetween the two chambers. The check valve permits only flow from the IFPchamber to the main oil chamber. With the check valve in parallel withthe orifice, the check valve insures that, if a high pressure eventforces fluid through the orifice into the IFP chamber, the force of thespring behind the IFP will quickly return that fluid to the main oilchamber through the low resistance path of the check valve once the highpressure event is over. This insures that a high pressure event doesn'tcause a long-term “dead band” in the cylinder because the cylinder haseffectively lost fluid from the main oil chamber into the IFP chamber.The check valve in parallel with the orifice provides the ability toachieve high pressure in both compression and extension. Without theorifice, either high pressure could be achieved in only one direction,or a very stiff spring would have to be used behind the IFP. A verystiff spring is undesirable because it takes up a lot of space, and inthe case of a standard cylinder (shaft on only one side of the piston),it limits the minimum force required to compress the cylinder. In thecurrent invention (microprocessor controlled ankle), we have athrough-rod cylinder (shaft on both sides of the piston). The IFP isneeded to accommodate volume changes due to temperature changes as wellas oil loss over time. Thus the orifice in parallel with the check valvein front of the IFP allows the cylinder to achieve high pressure in bothdirections while using a reasonably small and compact spring behind theIFP.

Volume compensation in the hydraulic cylinder can be provided in orderto allow for the change in the oil volume as the hydraulic cylinderheats up or cools down, and to allow for the change in the volume of thecylinder as compression occurs and the rod enters the cylinder in thecase of a cylinder that doesn't have a through rod. The volumecompensation can be provided with the independent floating piston (IFP)or a flexible bladder, but can also prevent or resist the hydrauliccylinder from generating high forces in both directions. In the exampleof a prosthetic ankle that uses a hydraulic cylinder, the ankle may notgenerate both sufficient plantarflexion (toe going down) resistance andsufficient dorsiflexion (toe going up) resistance. Thus, it can bedesirable to isolate the IFP from the main oil chamber with the floworifice 500, thereby making it possible for the cylinder to generatehigh forces in both directions while still having volume compensation.In addition, the check valve 502 can be placed in parallel with the floworifice 501, thereby preventing or resisting oil from getting trapped inthe IFP chamber in the case of an over-pressure event. If oil getstrapped in the IFP chamber, it can cause a dead band in the main oilchamber. A dead band in the main oil chamber can be a safety hazardsince it creates a region in which the cylinder can move with little tono resistance. Thus, the check valve prevents or resists a safetyhazard.

The prosthetic ankle 10 can include a power supply (such as batteries158) and a control module. In one embodiment, the control module caninclude a valve controller 160 carried by the hydraulic chamber 54 orhydraulic system, and disposed between the pair of arms of the yoke; anda main controller 162 disposed on both sides of the yoke). The actuator90 can be electrically coupled to the control electronics and powersupply to control and drive the actuator, and thus the operation of theprosthetic ankle.

The prosthetic ankle 10 can also have sensors associated therewith tomonitor the ankle, the artificial foot, their relative position, thegait cycle, the hydraulic system, etc. As stated above, the prostheticankle can include sensors, such as force or load sensor, torque sensor,angle sensor, accelerometer and/or gyroscope. These sensors can becarried by and disposed on the prosthetic ankle and/or artificial footitself. For example, a force or load sensor, a torque sensor, or acombination thereof 350, can be disposed on or coupled to the shank linkbetween the shank link and connector to measure force, torque, or bothapplied by the user to the prosthetic ankle or artificial foot. Theforce and torque sensor can be an integral part of the connector. Thetorque sensor can sense ankle torque in the sagittal plane. Variousaspects of robust and compact force and torque sensor are found in U.S.Pat. No. 8,746,080 (application Ser. No. 13/015,423, filed Jan. 27,2011), which is hereby incorporated herein by reference. It is desirablein prosthetic control systems to measure both the vertical force appliedto the product and the torque applied in the sagittal plane. Because thetorque generates strains that are much greater than those generated bythe force, it is difficult to design a single sensor that measures bothof these signals. As another example, an angle sensor 354 can be carriedby an ankle shaft of the pivot 22 between the shank link and theartificial foot to measure relative angle between the shank link and theartificial foot. As another example, an accelerometer, a gyroscope, or acombination thereof 358 can be carried by a foot coupler mount or theartificial foot to sense or measure impact, orientation, etc. Disposingthe sensors on the prosthetic ankle and/or artificial foot allows theprosthetic ankle to be a unitary device without components disposed onother structure, such as pylons. Similarly, locating an angle sensorbetween the shank link and the artificial foot allows relativeorientation to be determined without having to determine a relativeorientation of other structure, such as a pylon, and without having tolocate sensors on a pylon.

The control system can open the voice coil valve when the artificialfoot is un-weighted to allow the artificial foot to pivot with respectto the shank link to allow for terrain adaptation; and can close thevoice coil valve when the artificial foot is weighted to lock theartificial foot with respect to the shank link to allow the artificialfoot to function. The control system can utilize a control algorithm(s)that can smoothly transitions from a condition where ankle motion comesfrom both hydraulic cylinder motion and carbon fiber foot deflection, toa condition where the hydraulic cylinder is locked and continued anklemotion comes only from carbon fiber foot deflection. The position atwhich the hydraulic cylinder locks can be, at a minimum, a function ofthe patient's preference, the heel height of the current footwear,and/or the slope of the terrain.

The control system can include circuitry configured to enable acompliant ankle whenever the foot is un-weighted. The control systemcircuitry can be configured to lock the ankle at an appropriate anglebased on the position of the foot relative to the shank when weighted.The compliance enables the artificial foot to adapt to differentterrain. Locking the ankle allows for typical carbon fiber foot functionwhere the carbon fiber stores energy as the toe is weighted. This storedenergy helps propel the foot forward at toe off.

Referring to FIG. 16, the control module can initially be set to anun-weighted state as indicated by the arrow with no source state. In theun-weighted state, the valve is opened to allow the ankle to move whenthe foot makes initial contact with the ground. The amount the valve isopen is configurable and is set by the end user to provide a comfortablerate of movement as the foot progresses from initial contact with theground to being flat on the ground. This is noted in the diagram (FIG.16) as Valve Position=Plantarflexion Resistance. In another aspect, theplantarflexion resistance selected by the end user can also bedynamically adjusted from step to step by the control system toaccommodate, for example, changes in the slope of the terrain, gaitspeed, etc. The transition from the un-weighted state to the weightedstate can be triggered when a configurable force (weight) threshold isexceeded.

The weighted state can include different sub-states. An initial state isa ground search state. The ground search state sets the ValvePosition=Plantarflexion Resistance and transitions to the hydraulicdorsiflexion state when the foot is flat on the ground (foot flat). Footflat can be detected when the rate of hydraulic ankle angular rotationchanges in a positive direction, or when ankle movement changes from anegative direction to a positive direction. The foot flat condition canalso be detected by looking at ankle torque. In the hydraulicdorsiflexion state and during normal gait, the valve progressivelycloses over a period of time based on an algorithm. For example, thevalve position can be a linear function of the hydraulic ankle positionas illustrated by the equation:

$\begin{matrix}{{x = {{\frac{\left( {x_{CL} - x_{DFR}} \right)}{\left( {\theta_{T} - \theta_{FF}} \right)}\left( {\theta - \theta_{FF}} \right)} + x_{DFR}}},} & (1)\end{matrix}$

where

-   -   x=the current valve position,    -   x_(CL)=the valve position at which a valve orifice of the        control valve is completely closed,    -   x_(DFR)=the valve position selected by the amputee that produces        an amount of initial dorsiflexion resistance (dorsiflexion        resistance valve position),    -   θ=the current ankle position angle,    -   θ_(T)=the ankle position angle at which the hydraulic ankle will        switch to into a locked state, and    -   θ_(FF)=an ankle position angle when the foot of the device is        flat on the ground (flat foot) or when the device initiates a        hydraulic dorsiflexion state.

In another aspect, X_(DFR) can also be modified from step to step by thecontrol system to accommodate, for example, changes in the slope of theterrain, gait speed, etc. Additionally, θ_(T) can be determined for eachstep using:

θ_(T)=θ_(HH)+δ_(S)+δ_(P),  (2)

-   -   where    -   θ_(T)=the ankle position angle at which the hydraulic ankle        switches to the locked state (trigger angle),    -   θ_(HH)=a default ankle position angle at which a hydraulic ankle        switches to the locked state based on a heel height of the        current footwear,    -   δ_(S)=an offset angle from the default locked ankle position        based on the slope of the terrain, and    -   δ_(P)=an offset angle from the default locked ankle position        based on user preference.        Thus, the control system changes the position at which the        hydraulic resistance is applied based on patient's preference,        heel height of the footwear, and/or slope of the terrain using        algorithm (2). The sensors for detecting the slope of the        terrain and calculating δ_(S) for each step can include an        inertial measurement unit (IMU, accelerometer and gyroscope), a        ankle position sensor to detect an ankle position at foot flat,        a torque sensor to determine an amount of torque applied to the        ankle, etc.

In another embodiment, the control system can progressively close thevalve during the hydraulic dorsiflexion state using an algorithm thatemploys a non-linear progression from the dorsiflexion resistance valveposition to the closed valve position, as opposed to the linearprogression described above.

Hydraulic dorsiflexion can transition to the locked state once the ankleposition reaches the trigger angle determined using equation (2) in thepreceding paragraphs. In the locked state, the valve is commanded to thephysical end stop. In one example, the orifice(s) are not onlycompletely closed at the physical end stop, but there is also some spooloverlap to reduce the amount of fluid leaking through the valve. In thisexample, the hydraulic cylinder is then locked and the ankle will notarticulate any further. When the ankle will not articulate the foot willact like a traditional carbon fiber foot and provide expectedcharacteristics and performance.

In one configuration, the control system can be configured totransitioning from the weighted state to the un-weighted state onlyafter the patient has removed almost all of his or her weight from thefoot. Because the force is very small at this time, noise and/orinterference in the force signal can prevent the state transition fromoccurring at the correct time. Transitioning based on the torqueimproves the reliability of the transition because, even though theforce is small, it is typically applied to the toe of the foot at thetime of this transition, and even a small load applied to the toe cancreate a large torque. In another aspect, the control system can beconfigured to transition back to the un-weighted state at any time whilein the weighted state when the foot becomes un-weighted as detected bythe force sensor (weight). The un-weighted trigger is a variablethreshold.

The preceding paragraphs described operation of the control system of aprosthetic ankle that responds reliably and predictably because of thesimplicity of the control algorithm, while providing an algorithm thatis robust in that a single algorithm works well for level ground,slopes, and stairs. Referring to FIGS. 19 a and 19 b, the controlalgorithm can always use the same hydraulic resistance, but change theankle position (relative angle between the foot and the shank link) atwhich that hydraulic resistance is applied; as opposed to changing thehydraulic resistance, as shown in FIG. 19 b. The control algorithmand/or the control system circuitry can be configured to apply the samehydraulic resistance profile from step to step or from gait cycle togait cycle, but can also shift the hydraulic resistance profile earlieror later in the step or gait cycle, as shown in FIG. 19 a. Thus, thehydraulic resistance profile remains constant from step to step, or overa series of steps, or from gait cycle to gait cycle, but the controlalgorithm and/or the control system circuitry can be configured tochange where in the gait cycle the hydraulic resistance profile isinitiated or applied, as shown in FIG. 19 a. In addition, the controlvalve and the control algorithm and/or the control system circuitry canbe configured to change a position (ankle position or relative anglebetween the foot and the shank link) at which hydraulic resistanceoccurs, as shown in FIG. 19 a. Furthermore, a position of a hydrauliclock-out, such as a dorsiflexion stop, can change. Thus, the prostheticankle or hydraulic system does not have a hard stop, or a mechanicalstop, that is fixed, as shown in FIG. 19 b. The hydraulic system canprovide the hydraulic lock-out, such as the dorsiflexion stop, and theposition at which the hydraulic lock-out or the stop occurs can change.The hydraulic system can provide the hydraulic lock-out or the stopearlier or later in the gait cycle.

While in the un-weighted state, a transition into an inactive state canalso occur when a measurement from a sensor, such as a force sensor, atorque sensor or an ankle position sensor, decreases below aconfigurable threshold based on a detected motion of the foot. In oneaspect, the force, torque and ankle position sensors can be utilized. Inanother aspect, transition into the inactive state can occur when theoutput of the IMU decreases below a configurable threshold set to detectmotion of the foot. The combination of the force, torque, and ankleposition sensors used by the control system uses less power than theIMU. Thus, the force, torque and ankle position sensors can be on in thelow power sleep state, instead of the IMU. In addition, utilizing theforce, torque and ankle position sensors can provide a more reliabletransition between the inactive state and the active state because theankle position sensor can detect if the hydraulic ankle is moving, whilethe IMU can only detect if the entire foot is moving. In addition, theforce and torque sensors give subsequent information about whether ornot the user or patient has weight on the prosthetic ankle. Furthermore,using both force and torque information to switch between the inactivestate and the active state can provides more reliable behavior. In oneexample, when the control system is in the inactive state, a small forcecould be applied to the toe of the foot while the hydraulic ankle isagainst the dorsiflexion stop. In this case, the force may not exceedthe trigger set to transition back into the Active state, and the ankleposition sensor would not detect any movement because it is alreadyagainst the dorsiflexion stop; consequently, the torque would exceed thetrigger set to transition back into the Active state. The wait state isinitiated upon entering the inactive state. The transition to the sleepstate occurs after the elapsed time since entering the wait state isgreater than a configurable time limit. When the control algorithm hasentered a sleep state, the valve is turned off to save energy andimprove battery life. Other possible energy saving activities in thesleep state include: turning off other electronic systems (sensors,etc.) to save energy; going into a deep sleep state after another timedelay.

Having a low power “sleep” state (dependent on the force, torque, andankle rate of rotation) allows the prosthetic ankle to have a smallerbattery pack. In addition, the battery pack can be internal to theprosthetic ankle. It can be undesirable to have a large external batterypack that is attached via a tether and must be mounted to the outside ofthe prosthetic socket. This creates more work for the clinician to mountthe battery pack on the socket, causes reliability issues for thepatient when the tether fails, and makes the prosthetic leg lookunnatural because it has a battery pack attached to it.

The control system can include a connection via Bluetooth 1.0, 2.0, 3.0,or 4.0 (classic, high speed) and/or Bluetooth Low Energy (low speed)with a communications protocol that contains many networking standardelements, such as packet sequencing and checksums. The control system orcontroller can wirelessly connect to a user interface with a pair oftransceivers, each one carried by a different one of the prosthetic (andoperatively or electrically coupled to the controller) and the userinterface, and wirelessly connecting the user interface and thecontroller. The user interface can include a computing device with auser input, such as a tablet computer with a touch screen, a laptopcomputer, a desktop computer with a monitor, a cellular phone or smartphone, etc. A wireless connection between the user interface and theproduct is highly desirable in electronic prosthetic products. It allowsthe patient to move around freely unobstructed by wires while theprosthetist can easily make adjustments to the product on-the-fly or seeinformation coming from the product. However, an unreliable wirelessconnection can be more bothersome than the restrictions of a wiredsystem. In addition, the control system can, under the control of one ormore computer systems configured with executable instructions, open orbegin a “session”. During a session, information about the prostheticcan be sent by the controller to the user interface, including forexample, force, loads, torques and slopes measured me the sensors; gaitinformation such as gait cycle; hydraulic information such as hydraulicpressure, valve position, and power consumption; locking and unlockingpositions of the valve with respect to gait cycle or foot angle; batterylevel and output; etc. In addition, during a session, controlinformation or commands can be sent to the controller, including forexample, user preferences on heel height, position of locking andunlocking of the valve; the ankle position at which the hydraulic anklewill trigger into the locked state; the default ankle position at whichthe hydraulic ankle will trigger into the locked state as determined bythe heel height of the current footwear; an offset to the default lockedankle position based on the slope of the terrain; an offset to thedefault locked ankle position based on user preference; etc. A sessionbegins upon the first connection and continues until the application isclosed. If a wireless connection is broken (likely due to a weak signal)the software will automatically attempt to reconnect for a period oftime. If a reconnection is made, the previous state of the session willresume where it left off or at the point of termination. In many cases,the user may not even know that the connection had been broken and thenre-established. The purpose of this mechanism is to create a seamlessexperience for the user, even if/when the patient walks out of range forbrief periods of time. The session allows the wireless connection to bemomentarily interrupted with minimal impact. Most of the time, theprosthetist may not even know the wireless connection was eveninterrupted. This provides for a more positive user experience.

As stated above, and referring to FIGS. 12 a-c, the ankle can include ahousing 400 that can be disposed around a majority of the ankle. Thehousing 400, the shank link 14 and the artificial foot 18, and thehydraulic actuator or damper 40, can be disposed in an anatomicalenvelop of a natural leg. The control system and the battery can bedisposed in the housing. Thus, the control system and the battery can bedisposed in an anatomical envelop of a natural leg.

Referring to FIGS. 17 a-17 d, another hydraulic actuator or damper 50 bis shown that is similar in many respects to that described above, andwhich description is hereby incorporated herein by reference. Thehydraulic actuator or damper 50 b includes a mechanical ball lock 450 aspart of the prosthetic ankle or joint to lock or lockout the prostheticankle or joint, and is an integral or integrated part of the hydrauliccylinder. Thus, the need for a separate mechanism to provide locking isavoided, making the prosthetic ankle compact and lightweight.

As described above, the mechanical ball lock can lock the prostheticankle. The prosthetic ankle can have a large range of motion (e.g. 30degrees), and can provide many advantages (such as comfort whilesitting, the ability to use footwear with high heels, the ability to goup and down steep hills or ramps, etc.). In addition, the large range ofmotion and/or the hydraulic system can also pose a safety risk. Themechanical lock can be engaged by the patient to mitigate safety risks.The mechanical lock can be used to improve safety in the case of asystem failure such as a dead battery, a broken wire, etc. It can alsobe used to improve safety in situations where the patient would not wantany unexpected ankle motion to occur, such as driving a car, climbing aladder, etc. In addition to improved safety, the mechanical lock canalso provide convenience for the clinician. The clinician can lockoutthe ankle during dynamic alignment of the prosthetic leg using themechanical lock. This allows the clinician to focus on the alignmentwithout having to worry about the hydraulic settings at the same time.

The mechanical ball lock 450 can be carried by a piston rod 62 b of thehydraulic piston 58, and can releasably engage with the hydraulicchamber or cylinder 54 b, to lock the hydraulic piston and the hydraulicchamber with respect to one another. A collar 454 can be rigidly affixedto the hydraulic chamber or cylinder 54 b. The collar can extend fromthe cylinder and can have an axial bore or through hole therein forslidably receiving or concentrically receiving the piston rod 62 b. Thecollar can extend from the lower cap 72 b, or can be formed integrallywith the lower cap 72 b, of the chamber or cylinder. In addition, thecollar or interior thereof can have an indentation 458 therein. Theindentation 458 can be an annular groove circumscribing an interior orthe collar, and the piston rod. The piston rod 62 b extends through thecollar 454 and hollow thereof. In addition the piston rod 62 b has ahollow or axial hollow therein, and at least one hole 462 therethrough.The hole 462 can extend laterally or radially through the piston rod orwall thereof. In one aspect, the hole can comprise four holes. At leastone ball 466 is movably disposed in the at least one hole 462 of thepiston rod. The at least one ball 466 can move concentrically in thedirection of the at least one hole 462. In one aspect, the ball cancomprise four balls. In normal operation of the prosthetic ankle, theball(s) can reside in the hole(s), as shown in FIG. 17 d. When the balllock 450 is operated, the ball(s) an extend partially out of the hole(s)and partially into the indentation 458 or annular groove in the collar454 to lock the collar and the piston rod with respect to one another,and thus the piston and chamber or cylinder with respect to one another,as shown in FIG. 17 c. An engagement pin or plunger 470 can be movablydisposed in the hollow of the piston rod 62 b. The pin or plunger canhave an enlargement 474 to displace the at least one ball partially intothe indentation in the interior of the collar when the indentation isaligned with the at least one hole so that the at least one ball is inboth the at least one hole and the indentation to lock the piston rodand the collar with respect to one another, as shown in FIG. 17 c. Inaddition, the pin or plunger can have a reduction or reduced portion 478that receives or partially received the ball(s) therein in the normaloperation of the prosthetic ankle, as shown in FIG. 17 d. The pin orplunger can have a first position corresponding to the normal operationof the prosthetic ankle, in which the reduction or reduced portionaligns with the indentation 458 or annular groove in the collar 454, andallows the ball(s) to move out of the indentation 458 or annular groovein the collar 454, and defining an unlocked position. The pin or plungercan have a second position corresponding to and defining a lockedposition, in which the ball(s) and the hole(s) are aligned with theindentation 458 or annular groove in the collar 454, and the enlargementis aligned with indentation 458 or annular groove in the collar 454. Aspring can bias the pin or plunger in the locked configuration when thelock is engaged for safety purposes. In addition, the pin or plunger canbe retained in the unlocked position until engaged. In one aspect, thepin or plunger can be positively retained, such as with a pin, a setscrew, or the like.

Referring to FIGS. 18 a-d, another prosthetic ankle 10 c and foot isshown that is similar in most respects to that described above, andwhich description is hereby incorporated herein by reference. Theprosthetic ankle has optional, interchangeable cap 600 and snap-on bondring 604 removably coupled to the housing 400 c. For users or patientsthat do not want to cosmetically finish the prosthetic ankle (i.e. makeit have the shape of a natural leg), the cap 600 can be attached to thetop of the housing. The cap can be attached with a snap fit. For usersor patients that want to cosmetically finish the prosthetic ankle (i.e.make it have the shape of a natural leg), the snap-on bond ring 604 isremovably attached to the housing 400 c. A foam cover 608 can be bondedto the bond ring 604 that has the shape of a natural leg. The user orpatient can then pull a stocking or sock over the prosthetic ankle, footand foam cover to look like a natural leg. The bond ring 604 has a flatsurface on the top to make it easy to bond foam to. It can be difficultto cosmetically finishing a prosthetic ankle with 30 degrees of anklemotion because of the lack of foam materials that can endure thestretching and compressing that would be necessary if the foam wereattached to the top of the foot shell as is typical with a rigid carbonfiber foot with no hydraulic ankle. The foam can quickly break down andneeds to be replaced. Thus, the foam cover can be attached to the top ofthe prosthetic ankle, thereby avoiding the stretching and compressing ofthe foam when the ankle moves. Attaching the foam cover to the top ofthe prosthetic ankle instead of the foot shell also has the advantagethat it makes it easy to remove and/or replace the prosthetic ankle ifneeded, for example, in the case when the ankle needs to be repaired.Instead of cutting into the foam, the foam can simply be separated fromthe ankle by snapping off the bond ring.

In addition, the battery of the prosthetic foot can be charged usingelectromagnetic resonant wireless charging to allow patients to chargetheir prosthetic without taking off their prosthetic leg or removing abattery pack for charging. It also facilitates hands-free, worry-freecharging. For example, a charging transmitter could be mounted below acouch at home, a car seat, and a chair at the office so that every timethe patient sits in one of these locations, the prosthetic leg startscharging automatically with no input from the patient. It would alsoallow bilateral amputees to charge both prosthetic legs at the sametime. In addition, many patients prefer to cover their prosthetic legwith foam to make it have the same shape and size as a natural leg. Thismakes it difficult or impossible to access charging points or batterycompartments. This technology would allow battery charging through thefoam cover.

A single or multiple electromagnetic resonant transmitter(s) or sourcecan be tuned to two or more devices as a primary power source, withoutthe need of being spatially aligned to the receiver or coil or powercapturing devices. An oscillating magnetic field produces an electricfield and an oscillating electric field produces a magnetic field.Inductive chargers, such as those found commonly in electrictoothbrushes, operate on the principle of electromagnetic induction.However, for these systems to operate efficiently, the primary coil(source or transmitter) and secondary coil (receiver or power capturedevice) must be located in close proximity and carefully positioned withrespect to one another. This method enforces a limitation of tightspatial alignment of the power transmitter to the power receiver fordelivering the power. In addition, the close proximity requirements ofthe power transmitter to the integrated power receiver can be cumbersomefor an amputee as it could limit mobility or natural motion of limbswhile sitting or standing, etc. Strategically placed multiple magneticresonant transmitters or sources in the routine pathways of anamputee—in a home or office environment, shall allow perpetual chargingof the battery powered limb as they freely walk around—possiblyeliminating the complete loss of power to their battery poweredprosthetic limbs. This charging method could allow amputees to safelycharge their battery powered devices while driving a vehicle, virtuallyeliminating the risk of attached power cords (e.g. car charger)interfering with their foot work activity.

The Electromagnetic Resonant Charging method overcomes the limitationsof spatial alignment and articulation restriction of battery poweredprosthetic limbs as the power transmitter or source can be placedindependent of spatial alignment to the receiver or power capture sourcewith a proximity distance much larger than the inductive chargingmethod.

The charging method employs the wirelessly powered, magneticallycoupled, and resonantly tuned transmitter(s) and receiver(s). Magneticcoupling occurs when two objects exchange energy through their varyingor oscillating magnetic fields. Resonant coupling occurs when thenatural frequencies of the two objects are approximately the same. Powersources and capture devices are specially designed magnetic resonatorsthat efficiently transfer power over large distances via the magneticnear-field. These proprietary source and device designs and theelectronic systems that control them support efficient energy transferover distances that are many times the size of the sources/devicesthemselves.

It should be understood that many of the functional units described inthis specification have been labeled as modules, in order to moreparticularly emphasize their implementation independence. For example, amodule can be implemented as a hardware circuit comprising custom VLSIcircuits or gate arrays, off-the-shelf semiconductors such as logicchips, transistors, or other discrete components. A module can also beimplemented in programmable hardware devices such as field programmablegate arrays, programmable array logic, programmable logic devices or thelike.

Modules can also be implemented in software for execution by varioustypes of processors. An identified module of executable code can, forinstance, comprise one or more physical or logical blocks of computerinstructions, which can, for instance, be organized as an object,procedure, or function. Nevertheless, the executables of an identifiedmodule need not be physically located together, but can comprisedisparate instructions stored in different locations which, when joinedlogically together, comprise the module and achieve the stated purposefor the module.

Indeed, a module of executable code can be a single instruction, or manyinstructions, and can even be distributed over several different codesegments, among different programs, and across several memory devices.Similarly, operational data can be identified and illustrated hereinwithin modules, and can be embodied in any suitable form and organizedwithin any suitable type of data structure. The operational data can becollected as a single data set, or can be distributed over differentlocations including over different storage devices, and can exist, atleast partially, merely as electronic signals on a system or network.The modules can be passive or active, including agents operable toperform desired functions.

While the forgoing examples are illustrative of the principles of thepresent invention in one or more particular applications, it will beapparent to those of ordinary skill in the art that numerousmodifications in form, usage and details of implementation can be madewithout the exercise of inventive faculty, and without departing fromthe principles and concepts of the invention. Accordingly, it is notintended that the invention be limited, except as by the claims setforth below.

What is claimed is:
 1. A prosthetic ankle device, comprising: a) a pair of prosthetic members, comprising an shank link configured to be coupled to a remnant limb of an amputee and an artificial foot, movably coupled together to allow movement of the pair of prosthetic members with respect to one another; b) a hydraulic actuator or damper including hydraulic fluid in a hydraulic chamber coupled to one of the pair of prosthetic members, and a hydraulic piston movably disposed in the hydraulic chamber and coupled to another of the pair of prosthetic members; c) a hydraulic flow channel fluidly coupled between opposite sides of the chamber to allow hydraulic fluid to move between the opposite sides of the chamber as the hydraulic piston moves therein; d) a control valve coupled to the hydraulic flow channel to vary resistance to flow of hydraulic fluid through the flow channel, and thus movement of the piston in the chamber, and thus influencing a rate of movement of the pair of prosthetic members with respect to one another; and e) a controller coupled to the control valve and having circuitry configured to change a position at which resistance is applied by the control valve to the hydraulic fluid.
 2. The prosthetic ankle device in accordance with claim 1, wherein the controller circuitry is configured to control the control valve based on patient preference, a heel height of footwear coupled to the artificial foot, or the slope of the terrain.
 3. The prosthetic ankle device in accordance with claim 1, wherein the control valve opens or closes flow of hydraulic fluid through the flow channel, and thus allows or disallows movement of the piston in the chamber, and thus unlocks or locks movement of the pair of prosthetic members with respect to one another.
 4. The prosthetic ankle device in accordance with claim 1, wherein the controller circuitry is configured to control the control valve using: ${x = {{\frac{\left( {x_{CL} - x_{DFR}} \right)}{\left( {\theta_{T} - \theta_{FF}} \right)}\left( {\theta - \theta_{FF}} \right)} + x_{DFR}}},$ where x=a current valve position, x_(CL)=a valve position at which a valve orifice of the control valve is completely closed, x_(DFR)=a valve position angle selected by the amputee that produces an amount of initial dorsiflexion resistance, θ=a current ankle position angle, θ_(T)=an ankle position angle at which the hydraulic ankle will switch to a locked state, and θ_(FF)=an ankle position angle when the foot of the device is flat on the ground or when the device initiates a hydraulic dorsiflexion state.
 5. The prosthetic ankle device in accordance with claim 4, wherein the controller circuitry is configured to control the control valve using: θ_(T)=θ_(HH)+θ_(S)+δ_(P), where θ_(T)=the ankle position angle at which the hydraulic ankle switches to the locked state, θ_(HH)=a default ankle position angle at which a hydraulic ankle switches to the locked state based on a heel height of the current footwear, δ_(S)=an offset angle from the default locked ankle position based on the slope of the terrain, and δ_(P)=an offset angle from the default locked ankle position based on user preference.
 6. The prosthetic ankle device in accordance with claim 1, wherein the control valve comprises a voice coil valve.
 7. The prosthetic ankle device in accordance with claim 1, wherein the artificial foot is pivotally coupled to the shank link, and further comprises: a flexure mounting the hydraulic actuator or damper to the shank link or the artificial foot, and having a high stiffness in a direction parallel to a line-of-action of the hydraulic chamber to effectively transmit forces to and from the chamber, and having a low stiffness in at least one direction perpendicular to the line-of-action to resist side loads from being transmitted to the chamber.
 8. The prosthetic ankle device in accordance with claim 1, further comprising: a) a mechanical ball lock carried by a piston rod of the hydraulic piston, and releasably engagable with the hydraulic chamber, to lock the hydraulic piston and the hydraulic chamber with respect to one another, the mechanical ball lock comprising: b) a collar rigidly affixed to the hydraulic chamber; c) an indentation in the interior of the collar; d) the piston rod extending through the collar and having a hollow therein; e) at least one hole in the piston rod; f) at least one ball movably disposed in the at least one hole of the piston rod; g) an engagement pin movably disposed in the hollow of the piston rod; and h) the engagement pin having an enlargement to displace the at least one ball partially into the indentation in the interior of the collar when the indentation is aligned with the at least one hole so that the at least one ball is in both the at least one hole and the indentation to lock the piston rod and the collar with respect to one another.
 9. A prosthetic ankle device, comprising: a) a pair of prosthetic members, comprising an shank link configured to be coupled to a remnant limb of an amputee and an artificial foot, movably coupled together to allow movement of the pair of prosthetic members with respect to one another; b) a hydraulic actuator or damper including hydraulic fluid in a hydraulic chamber coupled to one of the pair of prosthetic members, and a hydraulic piston movably disposed in the hydraulic chamber and coupled to another of the pair of prosthetic members; c) a hydraulic flow channel fluidly coupled between opposite sides of the chamber to allow hydraulic fluid to move between the opposite sides of the chamber as the hydraulic piston moves therein; d) a control valve coupled to the hydraulic flow channel to open or close flow of hydraulic fluid through the flow channel, and thus allow or disallow movement of the piston in the chamber, and thus unlock or lock movement of the pair of prosthetic members with respect to one another; e) a controller coupled to the control valve; and f) the controller having circuitry configured to change a position at which resistance is applied by the control valve to the hydraulic fluid.
 10. The prosthetic ankle device in accordance with claim 9, wherein the controller circuitry controls the control valve based on patient preference, a heel height of footwear coupled to the artificial foot, or the slope of the terrain.
 11. The prosthetic ankle device in accordance with claim 9, wherein the controller circuitry is configured to control the control valve using: $x = {{\frac{\left( {x_{CL} - x_{DFR}} \right)}{\left( {\theta_{T} - \theta_{FF}} \right)}\left( {\theta - \theta_{FF}} \right)} + x_{DFR}}$ where x=a current valve position, x_(CL)=a valve position at which a valve orifice is completely closed, x_(DFR)=a valve position which produces an amount of initial dorsiflexion resistance preferred by the amputee, θ=a current ankle position angle, θ_(T)=an ankle position angle at which the hydraulic ankle will switch to a locked state, and θ_(FF)=an ankle position angle when the foot of the device is flat on the ground or when the device initiates a hydraulic dorsiflexion state.
 12. The prosthetic ankle device in accordance with claim 11, wherein the controller circuitry is configured to control the control valve using: θ_(T)=θ_(HH)+δ_(S)+δ_(P), where θ_(T)=the ankle position angle at which the hydraulic ankle switches to the locked state, θ_(HH)=a default ankle position angle at which a hydraulic switches to the locked state based on a heel height of the current footwear, δ_(S)=an offset angle from the default locked ankle position based on the slope of the terrain, and δ_(P)=an offset angle from the default locked ankle position based on user preference.
 13. The prosthetic ankle device in accordance with claim 9, wherein the control valve comprises a voice coil valve.
 14. The prosthetic ankle device in accordance with claim 9, wherein the artificial foot is pivotally coupled to the shank link, and further comprises: a flexure mounting the hydraulic actuator or damper to the shank link or the artificial foot, and having a high stiffness in a direction parallel to a line-of-action of the hydraulic chamber to effectively transmit forces to and from the chamber, and having a low stiffness in at least one direction perpendicular to the line-of-action to resist side loads from being transmitted to the chamber.
 15. The prosthetic ankle device in accordance with claim 9, further comprising: a) a mechanical ball lock carried by a piston rod of the hydraulic piston, and releasably engagable with the hydraulic chamber, to lock the hydraulic piston and the hydraulic chamber with respect to one another, the mechanical ball lock comprising: b) a collar rigidly affixed to the hydraulic chamber; c) an indentation in the interior of the collar; d) the piston rod extending through the collar and having a hollow therein; e) at least one hole in the piston rod; f) at least one ball movably disposed in the at least one hole of the piston rod; g) an engagement pin movably disposed in the hollow of the piston rod; and h) the engagement pin having an enlargement to displace the at least one ball partially into the indentation in the interior of the collar when the indentation is aligned with the at least one hole so that the at least one ball is in both the at least one hole and the indentation to lock the piston rod and the collar with respect to one another.
 16. A prosthetic ankle device, comprising: a) a pair of prosthetic members, comprising an shank link configured to be coupled to a remnant limb of an amputee and an artificial foot, movably coupled together to allow movement of the pair of prosthetic members with respect to one another; b) a hydraulic actuator or damper including hydraulic fluid in a hydraulic chamber coupled to one of the pair of prosthetic members, and a hydraulic piston movably disposed in the hydraulic chamber and coupled to another of the pair of prosthetic members; c) a hydraulic flow channel fluidly coupled between opposite sides of the chamber to allow hydraulic fluid to move between the opposite sides of the chamber as the hydraulic piston moves therein; d) a control valve coupled to the hydraulic flow channel to open or close flow of hydraulic fluid through the flow channel, and thus allow or disallow movement of the piston in the chamber, and thus unlock or lock movement of the pair of prosthetic members with respect to one another; e) a controller operatively or electrically coupled to the control valve; and f) the controller having circuitry configured to control the control valve using: ${x = {{\frac{\left( {x_{CL} - x_{DFR}} \right)}{\left( {\theta_{T} - \theta_{FF}} \right)}\left( {\theta - \theta_{FF}} \right)} + x_{DFR}}},$ where x=a current valve position, x_(CL)=a valve position at which a valve orifice is completely closed, x_(DFR)=a valve position which produces an amount of initial dorsiflexion resistance preferred by the amputee, θ=a current ankle position angle, θ_(T)=an ankle position angle at which the hydraulic ankle switches to a locked state, and θ_(FF)=an ankle position angle when the foot of the device is flat on the ground or when the device initiates a hydraulic dorsiflexion state.
 17. The prosthetic ankle device in accordance with claim 16, wherein the controller is further configured to control the control valve using: θ_(T)=θ_(HH)+δ_(S)δ_(P), where θ_(T)=the ankle position angle at which the hydraulic ankle switches to the locked state, θ_(HH)=a default ankle position angle at which a hydraulic switches to the locked state based on a heel height of the current footwear, δ_(S)=an offset angle from the default locked ankle position based on the slope of the terrain, and δ_(P)=an offset angle from the default locked ankle position based on user preference.
 18. The prosthetic ankle device in accordance with claim 16, wherein the control valve comprises a voice coil valve.
 19. The prosthetic ankle device in accordance with claim 16, wherein the artificial foot is pivotally coupled to the shank link, and further comprises: a flexure mounting the hydraulic actuator or damper to the shank link or the artificial foot, and having a high stiffness in a direction parallel to a line-of-action of the hydraulic chamber to effectively transmit forces to and from the chamber, and having a low stiffness in at least one direction perpendicular to the line-of-action to resist side loads from being transmitted to the chamber.
 20. The prosthetic ankle device in accordance with claim 16, further comprising: a) a mechanical ball lock carried by a piston rod of the hydraulic piston, and releasably engagable with the hydraulic chamber, to lock the hydraulic piston and the hydraulic chamber with respect to one another, the mechanical ball lock comprising: b) a collar rigidly affixed to the hydraulic chamber; c) an indentation in the interior of the collar; d) the piston rod extending through the collar and having a hollow therein; e) at least one hole in the piston rod; f) at least one ball movably disposed in the at least one hole of the piston rod; g) an engagement pin movably disposed in the hollow of the piston rod; and h) the engagement pin having an enlargement to displace the at least one ball partially into the indentation in the interior of the collar when the indentation is aligned with the at least one hole so that the at least one ball is in both the at least one hole and the indentation to lock the piston rod and the collar with respect to one another. 